The incidence of traumatic brain injury (TBI) in the United States is conservatively estimated to be more than 2 million persons annually with approximately 500,000 hospitalizations. Of these, about 70,000 to 90,000 head injury survivors are permanently disabled. The annual economic cost to society for care of head-injured patients is estimated at $25 billion. These figures are for the civilian population only and the incidence is much greater when combat casualties are included. In modern warfare (1993-2000), TBI is the leading cause of death (53%) among wounded who have reached medical care facilities.
Assessment of pathology and neurological impairment immediately after TBI is crucial for determination of appropriate clinical management and for predicting long-term outcome. The outcome measures most often used in head injuries are the Glasgow Coma Scale (GCS), the Glasgow Outcome Scale (GOS), computed tomography, and magnetic resonance imaging (MRI) to detect intracranial pathology. However, despite dramatically improved emergency triage systems based on these outcome measures, most TBI suffer long term impairment and a large number of TBI survivors are severely affected despite predictions of “good recovery” on the GOS. In addition, CT and MRI are expensive and cannot be rapidly employed in an emergency room environment. Moreover, in austere medical environments associated with combat, accurate diagnosis of TBI would be an essential prerequisite for appropriate triage of casualties.
Accordingly, the neural pathways of a mammal are particularly at risk if neurons are subjected to mechanical or chemical trauma or to neuropathic degeneration sufficient to put the neurons that define the pathway at risk of dying. A host of neuropathies, some of which affect only a subpopulation or a system of neurons in the peripheral or central nervous systems have been identified to date. The neuropathies, which may affect the neurons themselves or the associated glial cells, may result from cellular metabolic dysfunction, infection, exposure to toxic agents, autoimmunity dysfunction, malnutrition or ischemia. In some cases the cellular dysfunction is thought to induce cell death directly. In other cases, the neuropathy may induce sufficient tissue necrosis to stimulate the body's immune/inflammatory system and the mechanisms of the body's immune response to the initial neural injury then destroys the neurons and the pathway defined by these neurons.
Another common injury to the CNS is stroke, the destruction of brain tissue as a result of intracerebral hemorrhage or infarction. Stroke is a leading cause of death in the developed world. It may be caused by reduced blood flow or ischemia that results in deficient blood supply and death of tissues in one area of the brain (infarction). Causes of ischemic strokes include blood clots that form in the blood vessels in the brain (thrombus) and blood clots or pieces of atherosclerotic plaque or other material that travel to the brain from another location (emboli). Bleeding (hemorrhage) within the brain may also cause symptoms that mimic stroke. The ability to detect such injury is lacking in the prior art.
Mammalian neural pathways also are at risk due to damage caused by neoplastic lesions. Neoplasias of both the neurons and glial cells have been identified. Transformed cells of neural origin generally lose their ability to behave as normal differentiated cells and can destroy neural pathways by loss of function. In addition, the proliferating tumors may induce lesions by distorting normal nerve tissue structure, inhibiting pathways by compressing nerves, inhibiting cerebrospinal fluid or blood supply flow, and/or by stimulating the body's immune response. Metastatic tumors, which are a significant cause of neoplastic lesions in the brain and spinal cord, also similarly may damage neural pathways and induce neuronal cell death.
Identification and development of proteolytic products as biomarkers and/or diagnostic markers has been primarily focused within the confines of the CNS. Damage to peripheral nerves, such as occurred with diabetic neuropathies or administration of chemo-therapeutic agents such as those used to treat cancer, can also involve proteolytic damage similar to that seen in the CNS. Moreover, since protease activation is a major theme during cell injury in other organ injury (such as liver, kidney, lung, gut, heart etc.), or skeletal muscle overtraining and cancer cell proliferation or chemotherapy-induced tumor cell death and tumor shrinkage, this invention has a board-based application in diagnostics and monitoring of various organ injuries, multiple organ injury, CABG, sepsis, hyperventilation induced lung injury, muscle overtraining, cancer and the like.
There is thus, a need in the art for appropriate, specific, inexpensive and simple diagnostic clinical assessments of individual or multiple organ injury or stress, various organ-specific cancers and muscle training or overtraining, their severity and therapeutic treatment monitoring and efficacy assessment. Thus identification of proteolytic products of proteins or peptides that are specific to or predominantly found in a specific organ would prove immensely beneficial for both prediction of outcome and for guidance of targeted therapeutic delivery or muscle training and rehabilitation monitoring.